Pressure-control mechanism for pneumatic-dispatch systems



y o" J. v'r. cowLEY PRESSURE CONTROL MIIGIIANISMl FOR PNEUMATIC DISPATCH SYSTEMS 2 Sheets-Sheet 1 Filed Nov. 1922 Ma l0 1927.

y J. 'r. cowLEY FRESSURE CONTROL IECHANISM FOR PNEUMATIC DISPATCH SYSTEMS Fil'ed Nov. s. 1922 -2 shets-sneef .2

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Patented May 10, 1927.

j UNITED STATES PATENT. OFFICE.

` JAMES TQ COWLEY, OF SYRACUSENEW YORK, ASSIGNOR T0 THE LAMSON COMPANY,

` OF BOSTON, `MASSACHUET'lSl A CORPORATION 0F MASSACHUSETTS.

PRESSURE-CONTROL MECHANISM FOR PNEUMATIGDISPATCH SYSTEMS.

Application filed November 3, 1922. -Serial No. 598,877.

This invention pertains to power control mechanism tor use in pneumatic dispatch system and relates more specifically to that type of power controller which is automatically set into operation by the variation in `pressure in the transmission tube incident to the `introduction of a carrier therein. In pneumatic dispatch systems oi' the vacuum or low pressure type a slight. negative pressure is constantly maintained in the transmission tube and upon the introduction ot a` carrier the pressure within the tube in front ol the carrier is further slightly decreased due to the drag or inertia ot the carrier. This lowering ot' the pressure isicommonly depended upon to initiate the operation of means foropening a valve in a passage con uecting the transmission tube with a chamber in which' a relatively high vacuum is maintained, thus suddenly lowering the pressure in the transmission tube and producing a suction therein sutlicicnt to move the carrier rapidi toward the discharge end. Upon delivery ot the carrier, `it desirable immediately to restore the pressure condi tions in the tube substantially to normal in order to permit the operation to be repeated, but as the valve controlling means is sensi tive to even a small decrease inapressure below normal in the transmission tube and as the pressure in such tube at the time of delivery ot' the carrier is still Jar below the normal pressure, it is evident that some additional device must b e employed to assure closing of the valve. In some instances timing devices have been employed so arranged as to close the valve after a predetermined time interval irrespective of the position ot the carrier, but such devices are not as economical ot'. power as might be de sired, as the valve may remain open a considerable time after the carrier has been dis-` charged from the tube. either by reason ot` an unusually rapid passage of the carrier, or on account oi' the necessity of a Isecond openingI ot' the valve to complete the transmission of the carrier, such second opening taking place perhaps just prior to discharge o'l the carrier. The principal object of the 4present invention is to provide power corr trolling means uselul in pneumatic dispatch systems and more especially systems ol' the low pressure or vacuum type such as above referred to olf such character that while sensitively responsive to the slight decrease in pressure in the transmission tube resulting ltrom the introduction of a carrier thereln, it

`will be equally responsive to the slicht increase in pressure in the tube inciient to the delivery of the carrier therefrom, thereby assuring the prompt closing ot the valve and the restoration of normal pressure conditions-in the trai'ismission tube immediately ait'ter discharge of the carrier from the tube.

In accomplishing the above objects, the pressure valve is preferably actuated by a pneumatic motor ot usual type having a chamber which normally communicates 'freely with the transmisslon tube so that variations in pressure are quickly equalized in the tube and chamber, all in usual manner. In accordance with the present invention, provision is made for cutting off such i'rce communication between the motor chamber and tube immediately upon the occurrence of the sudden drop in pressure in the tube incident to the opening ot the main pressure valve, and so long such minimum pressure in the transmission tube continues, thepressure in the motor chamber is kept substantially constant and slightly below normal pressure by permitting the with-- drawal from and admission to the motor chamber of substantially equal and regulable quantities of air through restricted pas sages leading to the transmission tube and the atmosphere, respectively. Upon slight increase in pressure in the transmission tube due to discharge oi the carrier, the rate of withdrawal of air from the motor chamber `is thereby decreased, permitting pressure in such chamber to rise to normal, whereupon the main pressure valve is closed, restoring the parts to original position.

l'n the accompanying drawings one embodiment ol' the invention is illustrated by way of example and in such drawings:

Fig. l is a fragmentary side elevation of a portion oiia penumatic dispatch tube System showing the present power controlling device as applied thereto;

Fig. 2 is a vertical diametrical cross ser tion tl'irough the power controlling device on a line such as 2'-2 of Fig. 3 and to a larger scale than Fig. l;

Fig. 3 is a plan view of the device shown in Fig. 2;

Fig. 4 is a vertical cross section on a line such as 4-4, of Fig. 3 and to a somewhat `larger scale and ti t) Fig. 5 is a fragmentary vertical cross section upon the same plane as Fig'. 2 and showing the parts as occupying a different position from that ot Fig. 2. Referring tothe drawings, the numeral l indicates a'portion of a central station desk and the nunjieralQ designates one ot the several carrier transmission tubes which extend trom the various sub-stations to the central station. This tube is provided in the usual manner with a discharge tern'iinal f3 nor'- mallyclosed by a valve Vand` is continued as indicated at 5 beyond the discharge terminal and ends in a substantially horizontal portion 5a providing;` a chamber (3 ano constituting a` part oi" the casingv or housing); ot the controlling device hereinafter more Ytully described. The usual vacuum drum is indicated at 7. ik suction pipe or tube S is connected at one end to this drum while its other end terminates in the part 9 constituting a portion ot the casingY ot the controlliing device. The inner end of the chamber C projectsA transversely into a chamber l within' the part 9. The projecting' end ot' chamber G has opposed walls ll. l2 provided with openings in which tit the headif; lf3 and l-'l respectively ot' a balanced main pressure valve l5. Preferably the head llot this valve is furnished withguide tins 1G for centering itwithin its openingv when the valve is yopen. A port li' ot relatively small area provides communication between chamber G and the chamber 10. lf desired this port may be omitted and one or the otherot the valve heads7 as tor example the valve head 13, may be made to tit somewhat loosely in the corresponding;` openingv whereby to provide an annular port 1S connectingl the chamber 6 with the chamber l0. Il' desired both the port i7 and the port 1S may be employed.

The valve l is provided with a stem 19 which passes up through and is `guided within aV bore in a plate or cover 2O secured in an opening in the partition wall 2l eX- tending transversely across the casingv or housing. This partition wall is ot dished t rm havingl the rim portion 22 to which the peripheral portion 23 ot a cover member Qt yis .secured by means ot screws Q5. The edges of a tlei-:ible diaphragm 2G are claniped between the members 22 and This diaphragn'i 'forms a movable wall 'tor the motor chamber 27 thus provided between the diaphragm and the cover member 2l. The opposite side ot the diaphragm is always eX- posed to aftniospheric pressure by the provision ot a port 28 in the outer portion of the partition 2l. rl`he 'valve stem i9 passes up through the central part ot the diaphragm and the latter is clamped between a pair oi washers :29, 80, respectively, which are secured to the stem 19 by means ot a` nut; 31.

The central part ot the cover 24. is turythe stem i9.

nished with anA upstanding boss 32 having an internally screw threaded bore $33 in which n gland 34; is :nljustably mounted. This gland is provided with a central bore forming a Aguide 'tor a slidable auxiliary stem member arranged in alignment with The lower end ot this .stem member 35 is reduced in diameter and .screw threaded tor the reception ot a nut 'it'i. .i\V yoke member 3i' is clamped between tht` nut 3G and a shoulder at the lowin end ot the stem member Ifli and :i coiled .spring 21o .sur rounds the stem member Ila, bearing at onc, end iuiainst the yolre and bcinu received :it its` other cud within a socl-tet tl in the gland The cover member 27st is provided with a passage 40 opening' at tl into thc chamber (3 and at its other cud through the port -tl into the chamber QT. A\ second port l'i ot' much smaller area than the port'. also connects the passage it) with thi` chamber 2T and this port 4.2.1 may be controlled by meansl ot an adjustable ner-dlr valve llt ot usual type. The cover 2t is also provided with :i passage l5 opening to the atmosphere at one end and leadinu' hy means ot a port `tt'i :it its other end into the chamber QT. This port may also be regulated by means of a needle valve il-S ot usual type. lrelcrably another passage iti) (Fin: fi) leads 'trom the atmosphere to a port Tit) opening into the chamber 2T, and this port is also controlled by :i needle Yalve 51.

A bracket 52 is .secured to the inner side oll the cover 2i and this` braclict is provided with a tuhruni pin fifi upon which a lever .36 supported. lhis lcvcr has :in openingy for the passage ot the stein i5 and is provided at one end with a valve dish 53* cooiierable with the port llo vtor closing` thc latter and at its other end with a valve disk 5T cooperable with the port l2. pair ot springs 59, ti() are secured to .the lcvcr :'it' zuljacent to that end thercot havinu the valve disl-l 'l`he opposite ends ot these springs are secured rcsiliectivcly to brackets (d. o2 termineparts ot the yolte incii bei' Il?. 'l`hc stem l5) and thc auxiliary stein member iin are provided with aligned bores in which the opposite ends oi' a pin t are received. such pin serving` to maintain thc members li) and f in alignment. l

rlhe parts nornially occupy the position shown in Fig. .2 wherein thc port -l is wide open and port lti is entirely closed. tliediaphragin orruliyiiur its lowerniost position and conimunication between thc clnimbcrs o and l() being substantially cuiI oll' exi-cpt through the port-T l' and tu. When the parts are thus disposedthe low pressure maintained in the chamber T results in :i slight but constant llow ot air through the transmission tube in the direction ot the arrow AV in Fig. 2, the pressure in such tubo being thus maintained very slightly below too lui,

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atmospheric pressure. When a carrier is placed inthe tube the pressure 1n front of the carrier drops slightly due to the inertia :As the valve ,15 rises, the points of connection ot the springs 59, tl() with thc yoke member 37 also rise as shown in Fig. 5 until they pass `the horizontal plane ot` the fulcrlun pi1155. The `syn-ings thereupon immediately snap the lever 5G into the position shown in Fig. .fiwhercin the port 42 is closed and the port ttl opened. The closing of the port 42 cuts oil' communication between the motor chamber 27 and the transmission tube except t'or the restricted passage provided by the port 43. The only air which can now be drawn fromthe chamber 27 by the relatively high suction in the chamber (i mustbleed y through this restricted port itil, and the fill needle valves 444 and 48 are so adjusted that: the air passing out through the port 43 is substantially compensated for by air which bleeds in through the channel 45 and the now open port 4G. The pressure in chamber 2T is thus maintained substantially the same as that which existed therein at the instant ot upward movement of the diaphragm, even though tue pressure in the chamber (i is very much lower and the diaphragm thus remains in .its upper position holding the valve l5 open. `After the closing of valve 57', `the ditlerence in pressure upon its opposite sides assists the springs 5S), 6() in keep ingl it closed.

When the pressure in the transmission tube rises slightly above the transmission pressure, for example by reason of delivery ol' the carrier from the tube, the suction in the chamber ti decreases slightly so that the quantity ot' air drawn through the port 43 also decreases. As the air passage through the port 4G remains unchanged, pressure inimediately builds up in chamber 27 until the weight of the parts or the spring 38 acts to restore the diaphragm to its normal position. .f the diaphragm moves down the valve 15 is closed, but the independence ot' the stem members .I9 and 35 permits the opening of the port 42 to be slightly delayed. This delay is due partly to the arrangement ot the springs -59 and t3() which must be restored substantially to the position of Fig. 2 before the valve 57 is aiiiect-ed thereby and partly by the diti'erences in pressure upon the opposite sides of the valve. This delay serves to insure the complete closure of the main valve l5 before the port `42 is uncovered, this being necessary as otherwise the main valve would innnediately open again. lith this iuarngement accurate timing or relative 'adjustment of the parts is` made lli a second carrier were introduced into the tube prior to the discharge of the first,

the pressurein the tube will not substantially rise upon the discharge ot' the lirst carrier so that the diaphragm and the valve 15 will remain in the position shown in Fig. 5 until the discharge ot the second carrier. "lf he needle valve 5l with its port 50 permits a small amount of air to bleed into the chanr ber 27 under normal conditions so that there is no tendency to decrease the pressure .in the motor chamber beyond the normal amount prior to the introduction of a carrier into `the tube. This needle valve per-` mits a small quantity ot air to enter the chamber 2T even when the valve 57 is closed,

but the adjustment of the needle valve 4S is made such as to compensate t'or air leaking through the valve port 5t).

The arrangement above described provides eliicient and economi al means for controllingthe application ot power to the system and dispenses with the el'nployment ot controlling valve mechanism or similar des vices at the several sending stations. It also assures the closing of the main valve immediately upon the discharge ol. the last carrier in the tube so that there is no substantial loss of energy and the system .is imme` diately restored `to normal condition at'ter the completion otl each operation. While a specific arrangement oli parts has herein been shown, it is to be understood that the emlmdiment herein shown is illustrative only of the various embodiments ot means whereby the invention might readily `be carried into efi'ect.

I claim:

1. Power controlling apparatus for pneumatic dispatch systems comlgirising an air conduit, a valve controlling the tlow ot air ltlll llt) through said conduit, a pneumatit`I for actuating the valve, one side ol said pneumatic being freely exposed at all times` to atmospheric pressure and the other side thereof normally being exposed to the pressure ob taining in the conduit to one side of the valve, and means for restricting` eonmiunican tion between the conduit and the latter .side ot' the pneumatic comprising a normally open auxiliary valve and a spring alternatively operative to hold the auxiliary valve in open or closed position respectively.

Pneumatic dispatch apjiaratus having a transmission tube, au exhauster connected therewith, a valve t'or controlling the flow of carrier propelling air current through the transmission tube, a minimum flou' of ail' (lll through the tube being permitted when the valve is in closed position, and a pneumatic for operating the valve, one side of the pneumaticrbeing exposed freely at all times to atmos aheric pressure, means l'or determiningl the elllectvive pressure acting upon the oppm site side of the pneumatic, an auxiliary valve controlling a passage leading` :trom the transmission tube, a spring normally holding` said valve open, and means connecting'the spring to` the pneumatic so constructed and arranged that upon movement ot' the pneumatic 'from normal position the spring is so stressed as to close said auxiliary valve.

3. Pneumatic dispatch apparatus having a transmission tube, an exhauster connected therewith, a valve tor controlling the llow of carrier propelling' air current through the transmission tubeca minimum liow of air through the tube being permitted when the valvey is in closed position. and a pneumatic for operatingthe 'alve, one side olf the pneumatic being' eiqiosed freely at all times to atmospheric pressure, a normally open pivotally supported auxiliary valve lor controlling a passage leading from thc transmission tube to the opposite side olf the pneumatic. and spring means operative alternatively in accordance with .the position ol' the pneumatic to hold said auxiliary valve open or closedv respectively.

l. Pneumatic dispatch apparatus having a transmission tube, an exhauster connected therewith, a valve tor controlling the flow offV carrier propelling air current' through the transmission tube. a minimum tlow of air through the tube being permitted when the valve is invclosed position. and a pneumatic for operatingY the valve, one side olf the pneumatic being exposed freely at. all times to atmospheric pressure, a. pivoted lever` a. normally open auxiliary valve carried'` by the lever, said auxiliary valve con` trollingl a passage leading from the t ansmission tube to the opposite side ot the pneumatic, a spring having one endsecurcd to the lever, said spring normally being so stressed as to hold the valve open` and meansl actuatedv by the pneun'iaticy lor sluit ing the other end o'f the spring whereby to close the auxiliary valve.

5, Power control apparatus comprising in combination'with atransmission tube and a suctiontube, a valve lor controlling communieation, between said tubes` a pneuniatic motor havinga chamber provided with a movable Wall connected with the valve, ports connecting. thc-said chamber with the transmis-- sion. tube andV with the out air.. means normally closing the latter port. and means op* erative upon movement ot the movable wall ot the chamberin one direction tor opening the port: leading to the outer air and closing theport leading to the transmission tube.

6. -Power,- con-trol apparatus tor use with a pneumatic transmission tube, a suction tube, and a valve controlling communication therebetween, comprising a pneumatic motor having a chamber provided with a movable *all connected with the valve. a restricted port connectim r sanl chamber with the outer air. a relatively large port connecting the chaniber with the transmisxion tube. and valve means for alternatively closing one olI said ports and opening the, other.

'i'. Power control apparatus ot the class described comprising a pneumatic motor havingl a chamber provided with a movable side wall, means conncctiiig said chamber with a .space in which thc air pressure tluctuaies, .said means comprising' a relatively small port ot' adjustable capacity and a larger. normally unobstructcd port. a regulable port oi small capacity connecting the chamber with the atmosphere. a 'alvc normally closingl said latter port. a Isecond valve opcrable to closer tbe largo port. and means actuable by inward movement ol` .said movable wall to open .said iirst valve and close the second valve.

llower control apparatus comprisii'ig' a pneumatic motor having' a chamber closed at one side by a movable diaphragm, the diaphragm having a sliding lstem` a pair oll ports opening into the chamber. a lever l'ulcriuned within the chambcr. said lever hav ing an opening tor the passage ot' thc slidingI slcm ol the diaphragm, a valve member carried upon each cnd ot thtl lever. said valve members beingi` conalructed and arranged alternately to close the respective ports, and conmwtionsy len-tween the diaphragm and lever for actuating the latter.

t). lower control apparatusl comprising' a valve und a pneumatic motor l'or actuating it. said motor having a chamber, a dian phragm torming one wall lhcrcol'. a port leading' from the chamlicr to thc atmosphere, a second port leading from the cham ber to a space in which thc pressure fluctuales, a valve l'or closing' cach oi .said ports. one ot said 'alves being open when the other closed` and means comprisingV a resilient element .for suddenly changi'ing the relative positions o1" said valvll upon movement o'l" the diaphragm in either direction. the port leading' to the atmosphere normallyY being closed by its valve.

lt). A power controlling apparatus comA prising' ar main valve and a pnuematic motor for actuating it. said motor having a chamber closed atyone side by a diaphragm` :i stem connecting' the main valvc with the dialjihragm and projectingl into the chamber` a valve l'or deterulining the admission oll atuiosphcric air to the chamber. a spring normally positioned to hold said latter valve closed, and means connecting said spring with the valve stem so amstructcd and arranged that upon movement ol the dia- Til Htl

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lill) phragm from normal position the spring is so stressed as to open the air admission valve.

1l. A power controlling apparatus comprising a valve having a stem and a puen-` matic motor for actuating the` valve, said motor having a chamber closed at one side by a diaphragm, means connpcting the valve stem to the diaphragm, a pair of ports :for determining pressure conditions in said chamber, one of said ports opening to the atmosphere, valves for closing said ports, means so connecting said valves that when one is open the other is closed, and spring means operative alternatively, in accordance with the position of the diaphragm, for holding one ot.' said valves either in open or closed position, the valve associated with the port leading to the atmosphere normally being closed.

l2. A pneumatic motor for use in pneumatic systems comprising a housing having a chamber therein a diaphragm toi-ming one Wall of said c amber, a pair ot ports opening into the chamber, a lever tulcrumcd within the chamber, valves` mounted upon opposite ends of the lever and cooperable with the respective ports, a spring having one end secured to the lever normally arranged to hold one of said valves in closed position, and means moving with the diaphragm for so shifting said spring as to cause the other valve to be closed and the first valve to be opened.

13. A pneumatic motor for use in pncumatic conveyor systems comprising a housing having a chamber provided with a movable Wall, a port leading from the chamber to the atmosphere, a movable valve cooperating with the port, and a spring interposed betWeen the Valve and movable wall and so constructed and arranged that as the movable Wall approaches its limit of movement in either direction the valve moved suddenly from one extreme position to the other, the valve being normally positioned to close the port leading to the atmosphere.

14. A pneumatic motor for use in )new matic conveyor systems comprisingr a lhousing having a chamber therein, a diaphragm forming one Wall of the housing, a pair of ports for controlling pressure conditions Within the chamber, a lever pvoted Within the chamber carrying a valve member at either end, said valve members cooperating with the respective ports, a spring having one end connected to the lever and the other cud connected with the diaphragm, said lat-- ier end heilig movaliile upon movement of the diaphragm from a position at one side olf the l'ulcrum olf the lever to a position at the other side oit said ifulcrum whereby sud denly to swing the lever trom one extreme l'iosition to the other.

Power control apparatus comprising a pneumatic motel' having a chamber and a diaphragm forming one wall thereof, a valve controlled passage connecting said chamber with a space in which a negative and fluctuating air pressure is maintained, a valve controlled passage o't relatively small capacity connecting the chamber with the outer air, and a pair of simultaneously movable valves lor controlling said passages, said valves being actuablc by the diaphragm.

1 (3. A pneumatic motor for use in pneumatic dispatch systems comprising a housing having a chamber closed at one side by a diaphragm, a pair of ports provided `with needle valves opening into the chamber, a valve normally completely closing one of said ports, and means connecting said last named alve with the diaphragm whereby upon movement of the latter said valve moved to uncover its port.

17. A pneumatic motor for a carrier dispatch system comprising a housing having a chamber therein closed at one side by a movable diaphragm, a pair of ports connect-- ing said chamber with the outer atmosphere, said ports being provided with needle valves, a` valve i'nember normally completely clos .ing one ot said ports, a second pair ot ports opening into said chamber and connecting with a low pressure space, one ol" said latter ports being provided with a needle valve and the other being normally open and of relatively large capacity, avalve member for completely closing such larger port, means connecting said valve members for simultaneous but opposite movement toward and. from the ports with which they cooperate, and means connecting said valve members with the diaphragm for actuation thereby.

Signed by me at Syracuse, New York this 29th day ol September, 1922.

JAMES T. COWLEY.

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